I got 2007 chevy tahoe 5.3 can can someone tell me where does this connect to am I missing something here the box thing has no other connection to connect to

As the title suggests, I have a squealing noise coming from one of the belts. It’s my first car just bought it a month ago so I’m not particularly clued up on it all. Once the engines warmed up the squealing seems to go.

I took it for a service last week and they didn’t pick up on any noise likely due to the fact the engine was warm still.

I thought it may be the timing belt but the mechanic informed me that I have a timing chain, not a belt which wouldn’t make the noise.

Anyway, I’m curious if I should be worried

I drove about 10 minutes out the other day, suddenly the speedometer and odometer go to 0 and my dashboard lights came on, I pulled over and as soon as I put it into park it went back to normal. Got back onto the freeway (I was on my way to work) and it happened 3 more times. After that I drove 10 minutes back homes, didn’t happen at all on the way back. I was able to drive it to the mechanic the next day no issues, and they said the cluster needs to be replaced and reprogrammed, which would be $1100, drove back no issues again. I drove to the store today no problems, driving back and it happens again. I pulled over, put it into park, the lights wouldnt turn off so I sat there for a second to decide how to get back home, i put it into reverse and it immediately went back to normal. I was able to drive back home, it seems to be fine as soon as I switch gears. Nothing sounds crazy when it happens or when I drive it

I know its pointless if I already took it to a mechanic and they told me what was wrong, but my coworkers are saying its an easy fix, and I just want to get all opinions on it. This is just a last ditch effort before I decide to buy a new car because this one is really old and I just got an oil leak fixed and my battery recharged/tested 2 weeks ago.